Why is that only my right nipple could eract and not my left side?
Answers: You didn't stimulate it hard enough. Get someone to suck on it, or something..
Few women have both nipples fully developed unless or until they become pregnant.. Uneven development is more common than not. Sometimes a nipple will not respond, or even turn inwards, if there is breast cancer. See a doctor ASAP..
I know it has something to do with nerve endings
Maybe your nerve didn't fully grow out?
Or if you abuse painkillers, it can kill some nerves.
I have the same thing. we call it a lazy nipple. its always behind the other one. we need a picture to examine